Catalyst compositions similar to those of the present invention are disclosed in U.S. Pat. No. 3,736,354 which pertains to catalyst compositions containing the oxides of vanadium and molybdenum and one or more of the oxides of germanium, uranium, manganese, copper, gold and barium for the production of acrylic and methacrylic acids from acrolein or methacrolein. British Pat. No. 1,170,851 discloses catalyst compositions of the mixed oxides of molybdenum, vanadium and aluminum and an additional oxide such as germanium oxide, among others, for the production of acrylic acid from acrolein. However, the catalyst compositions of the present invention have heretofore not been disclosed wherein unexpectedly high yields of unsaturated carboxylic acids are obtained from the corresponding unsaturated aldehydes in the presence of these catalysts.